All equipment worn or carried by a creature is similarly enlarged by the spell. Melee weapons affected by this spell deal more damage (see Table: Medium/Large Weapon Damage). Other magical properties are not affected by this spell. Any enlarged item that leaves an enlarged creature's possession (including a projectile or thrown weapon) instantly returns to its normal size. This means that thrown and projectile weapons deal their normal damage. Magical properties of enlarged items are not increased by this spell.
The description of Enlarge Person implies that there are different sizes of ammunition, so one would assume that you need medium sized ammunition for a medium ranged weapon. If you don't have the appropriately sized ammunition, then you'll suffer a penalty to attack for using inappropriately sized weapons.
The cost for small ammunition is the same as for medium, and every size category over medium entails in a price increase of 2x.
All equipment worn or carried by a creature is similarly enlarged by the spell. Melee weapons affected by this spell deal more damage (see Table: Medium/Large Weapon Damage). Other magical properties are not affected by this spell. Any enlarged item that leaves an enlarged creature's possession (including a projectile or thrown weapon) instantly returns to its normal size. This means that thrown and projectile weapons deal their normal damage. Magical properties of enlarged items are not increased by this spell.The description of Enlarge Person implies that there are different sizes of ammunition, so one would assume that you need medium sized ammunition for a medium ranged weapon. If you don't have the appropriately sized ammunition, then you'll suffer a penalty to attack for using inappropriately sized weapons.
The cost for small ammunition is the same as for medium, and every size category over medium entails in a price increase of 2x.
The rules for weapons doesn't apply to ammunition unless it says it does. Shurikens get the green card, because they're only treated as ammunition for X purposes, and are otherwise light weapons.
In other news, yes, ammunition does have a size, and that size must be appropriate in order to fire with it. You can't use Large-sized Arrows for a Medium-sized Bow, and vice-versa.
though if you use enlarge person you'd want to have large arrows, to shoot, from your large, bow, because otherwise, the arrow will shrink back to med. dealing the same dmg. i.e.
large long bow, will shoot your enlaged med. arrow, just fine, but will still only deal 1d8 dmg, rather then 2d6.Note: that the large arrow will be huge, so the first time one attemps this, you need to note that you have released the arrow from your grasp, and catch it again before you knock the arrow.
your GM may require a dex, or a swift action or you may be able to refer to it as a free action, as if you were changing grop with any other weapon.
Or, if you're going to rely on Enlarge Archer as a spell, just bite the bullet and have a mount/animal companion/spear-carrier just hold those Large arrows you want to shoot.